Conventionally, an air-type shot-treatment machine is used for processing products by projecting shots at them. For example, products that have a plurality of gears coaxially disposed on a shaft with predetermined intervals, or products that have a plurality of gears coaxially disposed on a shaft in contact with each other, are processed by projecting shots while a support member to hold the products and a nozzle for projecting the shots are fixed in position.
However, for such a machine, the support member (to hold the gears) must he changed when the respective gears are replaced and processed. Thus, it takes much time to change the tooling for processing the products.
To solve this problem, an air-type shot-treatment machine having a nozzle that can ascend and descend is provided so as to avoid the change of the tooling being required when the respective gears are replaced and processed. (Sec Patent Document 1.)    Patent Document 1: Japanese Patent Laid-open Publication No. H8-216024